Mike Dirt and Billie Joe Armstrong may still be rocking out as the bassist and lead singer of punk-rock band Green Day (their new single “Bang Bang” was just released), but they also just started a line of sustainable coffee. Oakland Coffee Works is introducing the first coffee packaging made of certified compostable materials to several Bay Area stores.

Dirnt is calling their coffee the “fourth wave” that supports sustainable farmers and is packaged with completely biodegradable materials.

“Experts told us that there was no sustainable way to package the coffee it without going stale; it needs a one-way valve to breathe to prevent coffee from going stale,” Dirnt told The Daily Meal. “They said it couldn’t be done but I’m stubborn when people tell me I can’t do something. I push back against the status quo.”

Dirnt and Armstrong, who are longtime coffee drinkers, said that since the American Idiot World Tour, they’ve been bringing in artisan, small-batch coffee and roasting it backstage. It wasn’t until a few years ago that Armstrong asked Dirnt to start a coffee company with him.

Dirnt described their coffee as “low-acidity” without that “tangy, orange peel aftertaste.” Instead, he said, Oakland Coffee Works coffee tastes rich with lots of chocolate notes. “It’s not skinny jean coffee, but it’s not burnt either,” he said.

Starting Oct. 28, a three-pack of Oakland Coffee’s Gardenista blend — in 12-ounce coffee bags made from fully compostable materials — will be available at four Bay Area Costco stores for less than $20. A pair of 3-packs (that’s six 12-ounce bags total) will also be available on Costco.com for less than $45. Single 12-ounce bags of the organic Atomic Garden blend are available on Amazon.com, and the brand’s coffee pods will be available online and at stores nationwide by 2017.